The spine is divided into four regions comprising the cervical, thoracic, lumbar, and sacrococcygeal regions. The cervical region includes the top seven vertebral members identified as C1-C7. The thoracic region includes the next twelve vertebral members identified as T1-T12. The lumbar region includes five vertebral members L1-L5. The sacrococcygeal region includes nine fused vertebral members that form the sacrum and the coccyx. The vertebral members of the spine are aligned in a curved configuration that includes a cervical curve, thoracic curve, and lumbosacral curve.
A vertebral rod may be implanted to support and position a vertebral member in one or more of these regions. The vertebral rod extends along a section of the spine and may have a curved configuration to conform to the curvature and contour of the spine. The vertebral rod is connected to the spine with one or more anchors.
The anchors are inserted into the vertebral members to attach the vertebral rod. A connector attaches the vertebral rod to the anchor. The connector should be able to attach the vertebral rod and anchor when they are at a variety of different angular positions which is caused by factors such as the variably contoured surfaces of the vertebral members and the curvature and orientation of the vertebral rods.
The connector should provide a secure attachment of the vertebral rod to the anchor. The connector should also position the vertebral rod relative to the anchor to prevent the anchor from loosening from its purchase within the vertebral member when forces are applied to the vertebral rod.